Stool: Clostridium difficile common antigen and toxin/toxin gene
CT1905A: Positive/Positive CT1905B: Positive/Positive
CMPT QA/QC
CT1905-A: C.difficile common antigen positive and gene/toxin positive, viable for 51 days
CT1905-B: C.difficile common antigen positive and gene/toxin positive, viable for 51 days
Reference Laboratories
CT1905-A: 9/12 laboratories reported common antigen and toxin positive; 3 laboratories reported only toxin positive and did not test common antigen. 12/12 laboratories indicated they would report to IC/PH.
CT1905-B: 9/12 laboratories reported common antigen and toxin positive; 3 laboratories reported only toxin positive and did not test common antigen. 12/12 laboratories indicated they would report to IC/PH.
Participants’ results
| Table 1. CT1905A - Antigen/Toxin or Toxin gene | Total | Grade |
|---|---|---|
| Positive/Positive | 52 | Acceptable/Acceptable |
| Not tested/Positive | 6 | Ungraded/Acceptable |
| Total | 58 |
| Table 2. CT1905A - IC /PH Notification | Total | Grade |
|---|---|---|
| Yes | 57 | Acceptable |
| No | 1 | Unacceptable |
| Total | 58 |
| Table 3. CT1905B - Antigen/Toxin or Toxin gene | Total | Grade |
|---|---|---|
| Positive/Positive | 52 | Acceptable/Acceptable |
| Not tested/Positive | 6 | Ungraded/Acceptable |
| Total | 58 |
| Table 4. CT1905B - IC /PH Notification | Total | Grade |
|---|---|---|
| Yes | 56 | Acceptable |
| No | 2 | Unacceptable |
| Total | 58 |
NT: not tested
Suitability for Grading
A challenge is considered suitable for grading if agreement is reached by 80 percent of selected reference group and at least 70 percent of the participants.
Antigen and toxin detection was correctly performed by at least 80 percent of reference laboratories and greater than 70 percent of all laboratories thus, both challenges were determined to be suitable for grading.
Grading: Please note that grading for Clostridium difficile toxin testing has changed. Please click here for more details
The samples are assessed for homogeneity and stability using in-house quality control methods and random selection of samples before and during production, and post sample delivery. The number of random samples selected is based on selection tables within Military standard 105E (1).
The challenge sample lot was confirmed to be homogeneous and stable for at least 15 days.
Grading of Clostridium difficile common antigen and toxin/toxin gene detection is based on a Positive / Negative result, no further statistical analysis is performed on the results beyond that described under “Suitability for grading(1) Famum NR. Acceptance sampling. In: Modern Statistical Quality Control and Improvement. Belmont, California.: Duxbury Press; 1994:305.
